Antenna Types
This antenna unun kit is designed to be built for one of the two types of end fed antennas described below:
End Fed Half Wave
The End Fed Half Wave (EFHW) is known as a resonant antenna. This means it is designed to be used
without an antenna tuner. They are designed to be resonant on half wave multiples of its resonant
frequency. So an 80 meter EFHW is (theoretically) resonant on the 80, 40, 20, and 10 meter bands. This
isn’t completely true though since the bands aren’t exactly multiples of each other. To remedy this, you
can use a loading coil along the wire to bring other bands into resonance. However, many users find trimming the antenna for best SWR on the lowest half wave band will work well enough on even multiples. These antennas should be
deployed in the same fashion as a dipole, sloper, inverted vee, or even vertical if you use a feedline of at least 10 feet (longer is better as the shield of the coax can act as a counterpoise. A short counterpoise can be added on the "ground" wire, usually 5-15 feet is fine. Some users only use the coax shield as the counterpoise. It is absolutely amazing how well this works!
End Fed Random Wire, Rybakov (build as 9:1 or 4:1 UNUN)
The End Fed Random Wire (EFRW) antenna is not resonant and is designed to be used with an antenna
tuner. The antenna is essentially designed to be equally “out of tune” on a large range of frequencies,
such that a tuner can be used to bring the antenna into a match, and therefore be usable on many bands.
This is a great option for radios that have a built-in ATU or an external Antenna Tuner. With this type of antenna, you want to prevent the antenna from being resonant on any particular band. For finding the length you want, I recommend looking at an article
that the University of Delaware posted. It can be easily found by doing an internet search for “End fed random wire antenna lengths”
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